7.1 Longitude and Latitude

Any location can be pin-pointed by its longitude and latitude. Lines of latitude and longitude are printed on aeronautical charts (e.g., sectional) with each degree subdivided into 60 equal segments, or "minutes." By referring to your sectional chart, the location of your airport can be easily determined by the intersection of lines of latitude and longitude.

Lines of latitude are parallel to the equator; those north of the equator are indicated as 0° to 90° North latitude, those south of the equator are indicated as 0° to 90° South latitude. (As a pilot flying in the US, it's fair to assume that you'll primarily be operating in the Northern latitudes.)

Lines of longitude are lines which extend from the north pole to the south pole. The prime meridian (which passes through Greenwich, England) is 0° longitude with 180° on both the east and west sides of the prime meridian.

Ascent Quick Quiz

Ascent Quick Quiz - 7.1 Longitude and Latitude

Question 1: (Refer to figure 21, area 3.) Determine the approximate latitude and longitude of Currituck County Airport. Answer

Question 2: (Refer to figure 22, area 2.) Which airport is located at approximately 47°39'30"N latitude and 100°53'00"W longitude? Answer

Question 3: (Refer to figure 22, area 3.) Which airport is located at approximately 47°21'N latitude and 101°01'W longitude? Answer

Question 4: (Refer to figure 23, area 3.) Determine the approximate latitude and longitude of Shoshone County Airport. Answer

Question 5: (Refer to figure 27, area 2.) What is the approximate latitude and longitude of Cooperstown Airport? Answer

7.2 Using VOR Radials to Determine Location

There will be several exam questions that will require you to identify your location based on the intersection of two given VOR radials. To locate a position based on VOR radials, draw the radials on your chart or on the plastic overlay during the FAA knowledge test.

Remember that radials are FROM the VOR, or leaving the VOR.

Make sure you have located the correct radial on the compass rose before drawing your line. Double-check yourself by counting in 5° or 10° intervals from each of the closest 30° intervals that are numbered and marked with an arrow.

Other FAA exam questions require you to identify your position based upon the indications of a single VOR.

You must compare the OBS setting and the TO/FROM indicator with the aircraft heading. To indicate correctly, the OBS (top) setting must correspond roughly with the aircraft heading (e.g., 180° OBS (top) setting, 180° aircraft heading). The TO/FROM indicator must correspond to the aircraft's flight path in relation to the VOR.

Flying TO a VOR with a FROM indication and flying FROM a VOR with a TO indication will result in reverse sensing.

When flying directly from a station, the heading and the radial being flown will correspond (i.e., 360° heading FROM will be the 360° radial).

When flying directly TO a station, the heading flown and the radial being flown will be reciprocals (i.e., 180° heading TO will be on the 360° radial).

With regard to CDI deflection, you must pretend your airplane has the same heading as the OBS setting. A left deviation means you are right of course, and a right deviation means you are left of course.

1) If your heading and the OBS setting are not roughly the same, the CDI will not indicate correctly.

If no TO or FROM flag indication appears, the aircraft is in the area of ambiguity, i.e., 90° away from the radial dialed up on the OBS. To know the side of the station on which the aircraft is located, consult the CDI. The needle points toward the station.

Ascent Quick Quiz

Ascent Quick Quiz - 7.2 Using VOR Radials to Determine Location

Question 1: (Refer to figure 21.) What is your approximate position on low altitude airway Victor 1, southwest of Norfolk (area 1), if the VOR receiver indicates you are on the 340° radial of Elizabeth City VOR (area 3)? Answer

Question 2: (Refer to figure 24.) What is the approximate position of the aircraft if the VOR receivers indicate the 320° radial of Savannah VORTAC (area 3) and the 184° radial of Allendale VOR (area 1)? Answer

Question 3: (Refer to figure 25.) What is the approximate position of the aircraft if the VOR receivers indicate the 245° radial of Sulphur Springs VOR-DME (area 5) and the 140° radial of Bonham VORTAC (area 3)? Answer

Question 4: (Refer to figure 26, area 5.) The VOR is tuned to the Dallas/Fort Worth VORTAC. The omnibearing selector (OBS) is set on 253°, with a TO indication, and a right course deviation indicator (CDI) deflection. What is the aircraft's position from the VORTAC? Answer

Question 5: (Refer to figure 29, illustration 8.) The VOR receiver has the indications shown. What radial is the aircraft crossing? Answer

Question 6: (Refer to figure 29 and figure 27, areas 4 and 3.) The VOR is tuned to Jamestown VOR, and the aircraft is positioned over Cooperstown Airport. Which VOR indication is correct? Answer

Question 7: (Refer to figure 29, illustration 1.) The VOR receiver has the indications shown. What is the aircraft's position relative to the station? Answer

Question 8: (Refer to figure 29, illustration 3.) The VOR receiver has the indications shown. What is the aircraft's position relative to the station? Answer

Question 9: (Refer to figure 29 and figure 21, area 3.) The VOR is tuned to Elizabeth City VOR, and the aircraft is positioned over Shawboro. Which VOR indication is correct? Answer

Question 10: (Refer to figure 25 and figure 29.) The VOR is tuned to Bonham VORTAC (area 3) and the aircraft is positioned over the town of Sulphur Springs (area 5). Which VOR indication is correct? Answer

7.3 VORs and VOR Test Facility (VOT)

Certain airports have VOR Test Facilities (VOTs). These are facilities that transmit radio signals on certain discrete frequencies, allowing you to check the accuracy of your aircraft's VOR receiver while you are on the ground.

To utilize the VOT simply tune your aircraft's VOR to the specified VOT frequency, and use the OBS knob to center the course deviation indicator needle.

Regardless of your position or heading at the airport, the OBS should read either:

180° and TO on the TO/FROM indicator. Or,

0° and FROM on the TO/FROM indicator.

NOTE: Accuracy of the VOR must be within ±4°.

Ascent Quick Quiz

Ascent Quick Quiz - 7.3 VORs and VOR Test Facility (VOT)

Question 1: When the course deviation indicator (CDI) needle is centered during an omnireceiver check using a VOR test signal (VOT), the omnibearing selector (OBS) and the TO/FROM indicator should read Answer

7.4 Global Positioning System

The use of GPS (or, Global Positioning System) is becoming more and more prevalent in general aviation as a means of navigation. Many newer general aviation aircraft come factory-equipped with GPS navigation systems, and every month it seems there is a new portable GPS available on the market.

The Global Positioning System (GPS) is composed of a constellation of 24 satellites, placed in designed orbits that allow for at least five satellites to be in constant line-of-sight by a user anywhere on earth.

However, a GPS receiver needs only four satellites to yield a three-dimensional position (latitude, longitude, and altitude) and time solution.

GPS receivers are able to compute navigational solutions such as distance and bearing to waypoints (e.g., an airport), or groundspeed, etc., by using the airplane's known latitude/longitude (position) and referencing this to a database built into the receiver.

Ascent Quick Quiz

Ascent Quick Quiz - 7.4 Global Positioning System

Question 1: How many satellites make up the Global Positioning System (GPS)? Answer

Question 2: What is the minimum number of Global Positioning System (GPS) satellites that are observable by a user anywhere on earth? Answer

Question 3: How many Global Positioning System (GPS) satellites are required to yield a three dimensional position (latitude, longitude, and altitude) and time solution? Answer

7.5 Automatic Direction Finder (ADF)

Another type of navigational instrument found in aircraft is the Automatic Direction Finder, or ADF. The ADF is an instrument that works in conjunction with a ground-based nondirectional beacon, or NDB. The ADF functions simply by always having its need point directly toward the NDB to which the instrument is tuned to.

For example, if the NDB is directly in front of the airplane, the needle will point straight up.

If the NDB is directly off the right wing, i.e., 3 o’clock, the needle will point directly to the right.

If the NDB is directly behind the aircraft, the needle will point straight down, etc.

There are a few specific terms used when referencing navigation or instrument flying by the use of the ADF/NDB. The figure below should help to illustrate these terms. (When working ADF problems, it is often helpful to draw the information given - just like the figure below - to provide a picture of the airplane's position relative to the NDB station.)

Relative Bearing (RB) - Relative Bearing to the station is the number of degrees you would have to turn to the right to fly directly to the NDB. On a fixed card ADF, the

Relative bearing TOthe station is shown by the head of the needle.

In the figure below, the RB to the station is 220°.

Relative bearing FROMis given by the tail of the needle.

In figure below, the RB from the station is 40° (220 – 180).

Magnetic Bearing (MB) - Magnetic Bearing TO the station is the actual heading you would have to fly to the station. If you turn right from your present heading to fly to the station, you are adding the number of degrees of turn to your heading.

Question 7: (Refer to figure 30, illustration 1.) What is the relative bearing TO the station? Answer

Question 8: (Refer to figure 30, illustration 2.) What is the relative bearing TO the station? Answer

Question 9: (Refer to figure 30, illustration 4.) What is the relative bearing TO the station? Answer

Question 10: (Refer to figure 31, illustration 3.) The relative bearing TO the station is Answer

Question 11: (Refer to figure 31, illustration 1.) The relative bearing TO the station is Answer

Question 12: (Refer to figure 31, illustration 2.) The relative bearing TO the station is Answer

Question 13: (Refer to figure 31, illustration 4.) On a magnetic heading of 320°, the magnetic bearing TO the station is Answer

Question 14: (Refer to figure 31, illustration 5.) On a magnetic heading of 035°, the magnetic bearing TO the station is Answer

Question 15: (Refer to figure 31, illustration 6.) On a magnetic heading of 120°, the magnetic bearing TO the station is Answer

Question 16: (Refer to figure 31, illustration 6.) If the magnetic bearing TO the station is 240°, the magnetic heading is Answer

Question 17: (Refer to figure 31, illustration 7.) If the magnetic bearing TO the station is 030°, the magnetic heading is Answer

Question 18: (Refer to figure 31, illustration 8.) If the magnetic bearing TO the station is 135°, the magnetic heading is Answer

7.6 VHF/Direction Finder facility

The VHF/Direction Finder facility is a ground operation that can determine the magnetic direction of an airplane from the station each time the airplane transmits a signal to it. An air traffic controller can then give aid in the form of directional guidance to the aircraft. In order to take advantage of VHF/DF radio reception for assistance in locating a position, an airplane must have both a VHF transmitter and a receiver. The transmitter and receiver are necessary to converse with a ground station having VHF/DF facilities.

In the Airport/Facility Directory the letters "VHF/DF" appearing next to certain airports indicate that the Flight Service Station has VHF/Direction Finding equipment with which to determine your direction from the station.

Ascent Quick Quiz

Ascent Quick Quiz - 7.6 VHF/Direction Finder facility

Question 1: To use VHF/DF facilities for assistance in locating an aircraft's position, the aircraft must have a Answer

Question 2: The letters VHF/DF appearing in the Airport/Facility Directory for a certain airport indicate that Answer

7.7 Aircraft Transponder

1200 is the standard VFR transponder code. When operating under VFR below 18,000 ft MSL, the transponder code 1200 should be selected, unless otherwise instructed by ATC. Similarly, if ATC advises, "Radar service is terminated," the transponder should be set to code 1200.

The following codes are for use during aircraft emergencies only. Additionally, as they cause certain immediate responses from ATC, when making routine transponder code changes, pilots should avoid inadvertent selection of the following codes.